kill it with fire
I always remove the PCBA, crush that with a dead-blow hammer or drop it into a shredder to destroy all the embedded flash. For magnetic media, I take a screw gun to the drive and remove the platters, which then spend quality time under a propane torch or in a brazing furnace. Usually long enough that the plating blisters off and the aluminum platters melt. If I cannot access a torch, I'll grind the platters down in the machine shop, destroying the plating. After it cools, all the little bits and pieces can then go in the garbage / recycle bin.
A previous employer of mine had a history of buying used machines by the pallet load from a refurbisher; and, after a little forensics I found corporate data belonging to the prior owner(s). After that experience, I'll never let a drive out of my hands without doing the above.
Biting the hand that feeds IT
